class Rect {
  num height;
  num width;
  Rect(this.height, this.width);
  // area() {
  //   return this.height * this.width;
  // }
  get area {
    return this.height * this.width;
  }

  set areaHeight(value) {
    this.height = value;
  }
}

main() {
  Rect r = new Rect(10, 4);
  r.areaHeight = 6;
  print("面积：${r.area}");
}
